AFM-IR Mapping of <i>Escherichia coli</i> Disruption on Silver Nanoparticle-Coated Titanium: Dual-Function Surfaces for Antibacterial Implants

Titanium (Ti) is widely used in biomedical implants due to its favorable mechanical properties and biocompatibility. However, microbial colonization and biofilm formation on Ti surfaces remain major clinical challenges. In this study, Ti surfaces were modified with silver nanoparticles (AgNPs) to enhance antibacterial performance without compromising corrosion resistance. AgNPs were synthesized via chemical reduction and deposited onto polished Ti substrates. Their antimicrobial activity against <i>Escherichia coli</i> (<i>E. coli</i>) was evaluated using minimum inhibitory concentration (MIC) assays, while electrochemical measurements indicated that AgNPs coatings slightly improved corrosion resistance. Atomic force microscopy-infrared (AFM-IR) spectroscopy was employed to probe nanoscale structural and biochemical changes in bacterial cells. After 24 h of incubation, <i>E. coli</i> on bare Ti surfaces exhibited significant alterations in protein secondary structure. In contrast, bacteria on AgNPs-modified Ti displayed disrupted morphology and reduced biomolecular signals, indicating growth inhibition within the first hour. Principal component analysis (PCA) confirmed distinct spectral patterns associated with bacterial response over time. These findings demonstrate that AgNPs-functionalized Ti surfaces induce bacterial cell damage consistent with bacteriostatic and bactericidal effects, suggesting potential applications in the prevention of implant-associated infections.